Power Steering Gear Box Conversion Part Number (1 Viewer)

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Dec 23, 2010
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Hey Guys, I just picked up a Power Steering Gear Box and confirmed all the key characteristics. There seems to be quite a bit of confusion over part numbers and vendors, and variables on the gear box, so I wanted to let you know what I found in case you are interested.

When I was researching this part, I found a discrepancy in the input spline count, i think i understand why; the flat (key) on the shaft removes 4 of the splines, so if you count the splines, you count 32, if the flat was not machined in the shaft you would count 36.

Good luck, hope this helps.

4 mounting holes
4.25 turns lock to lock
13/16 diam input shaft
36 spline input shaft
1.25 diam output shaft
Flare fittings

Re-manufactured
O'reilly Auto parts (came in a cardone box) Part Number 27-6537
$116.99, with a $45 core charge. They will take the manual box as the core.


ps gear.jpg
ps gear.jpg
 
Yes, spline count is always determined by the number of teeth in a full 360 degree circle, and you must add teeth for the ground flat spot. Saginaw diameter/tooth counts for GM boxes are:
3/4" by 30 splines
3/4" by 36 splines
13/16" by 36 splines.
1980-older are SAE (American) threaded boxes, 1981-newer are metric threaded boxes.
Number of full turns in the box range from 2 (normally TransAM/Corvett quick ratio) to 4.5 full turns. This forum seems to like the 4.25 to 4.5 turn boxes, however the 3.5 turn boxes actually have a much better ratio when using dual stage valving.
 

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